Based on your description you are probably pretty close to the line if you don't also buy a good number of items and keep them. I say this as an Elite Plus member who has myself already spend $12k at Best buy this year and who last year almost hit $40k. I have never once triggered the return blacklist but I buy such a large number of high value items from them that I would be very surprised if I did. I did ask a few of them how that process worked a couple times out of curiosity. Unfortunately I will be returning my Samsung Galaxy S 8.4 today though as the battery life and CPU just can't be justified for me over my iPad Mini Retina with Cellular Data for my needs. I really wanted them to though with that screen.
In just this month I have bought from Best Buy
Samsung Galaxy Tab 4 8.0
Samsung Galaxy Tab Pro 8.4 (quantity 3) for my 2 sons and wife
Samsung Galaxy Tab S 8.4 for myself as a trial to replace my iPad Mini Retina
Microsoft Surface Pro 3 To replace my Lenovo Yoga Pro 2
Microsoft Surface 2 for my father in law
Nokia 521 Phone for my older son